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Letters Patent No. 72,520, datediecember 24, 1867. I

IMPROVEMENTS IN HOT-AIR PURNAGES.-

Specification ofv Improvements in Air-Heating Furnaces for Warming Dwellings, &c., inventcdby GEORGE F. MERKLEE, of the city, county, and State of New York. .Y

M'y improvements arevmade in the construction-of the lparts of an air-heating furnace above the tire-pot, therefore the ire-pot and parts below it need no specific description. l

My invention consists, first, in the peculiar forni of the plate whichl rests upon the top-rim of the fire-pot, and the tubes or airpassages arranged upon it,in combination-with the annular smoke-Hue extending upward beyondaid air-passageafor the purpose of providing a large'amount of heating-surface, and obliging the products of combustion to pass over the Whole ofsaidrsurface in their course to the exit-pipe; second, in the combination with annular iiueairpassages, and dome, of a cylinder extending downwards to a point about half the height, and within'the lin-e of the air-passages, for the purpose of preventing thehot products of combustion, which rise into the dome above the fire-pot, passing .too freely outvvard into the annular smoke-Hue, and, also,

for the purpose of equalizing the action of the smokeand gases upon 'the fire-surface of the ailpassages, by

holding them for a lon'gertime against said surface, While,.at the same time, thecylinder does not obstruct the reflection of the lire upon the said air-passages or tubes; third,`the combination, with the annular iiue, of a crossf pipe and central exit-pipe, whereby the products of combustion, which pass outward from the fire-pot, are returned to thecentre ofthe furnace before they can pass into the exit-pipe, and thence into the chimney. In the accompanying drawings, in which like letters refer to like parts- Figure 1 is a front elevation of the furnace, with outside cylinder or casings attached.

Figure 2 is a vertical central section of the furnace, taken from front to rear.

Figure 3 is a horizontal plan of the furnace, taken at the line W in iig.A 2.

Figure 4 :is a horizontal plan of the furnace, taken at'the line V in fig, 2.

G is a plate resting upon and forming a joint with the top rim of the fire-pot F, which plate extends upward and outward to a line Within the inner circle of the air-tubes or passages I I I I I, and thence outward horizontally beyond the outer circle of said air-passages to the cylinder M, with which it forms a joint. In the horizontal portionV of the plate G' is a series of-openings extending through i-t, to admitthe arto be heated to the air-passages I.

These tubes or air-passages extend upward from the plate G, through the combustion-chamber, outside of the cylinder'J, to the at plate K, with which they form a joint. Extending upward from the outerline of the plates G' and K are the cylinders L and M, which form the annular tiue I, which is closed at the top by the fiat plate S. Extending upward from the inner line of fthe flat plate K is the cylinder O O, which is closed at the top byplute P, forming the dome c. Extending across the air-chamber el, from the cylinder Ii, is the crosspipeQ, which connects the annular smoke-fine b with the exit-pipe R. Surrounding and enclosing the whole is thecylinder N, and top of same, U, which forms the air-chambery", into which the air to be heated is conveyed through the opening I), in the base A, and passing over the surfaces of the plates G, K, S, and I?, cylinders O,

L, M, and through the ailpassages I, passes through thel openings T to the tin pipes, thence to the diierent apartments which nieto be warmed. Y

My invention consists in giving to the plate G. the form shown iu drawings, figs. 2 and 3, for the purpose of remedying defects which have heretofore existed. In furnaces where tubular plates are used, it has been common, prior to my invention, to make them fiat, and it has also been claimed as new to make these plates to incline inward.anddowuwardfrom the cylinder M to the fire-pot F. In the dat plate, radiating surface is lost to a. very great extent, as it is not exposed to the direct action of the fire, andaccumulates upon it non-conducting substances. In thc inclined plate, where the inclination is great, the accumulation of non-conducting matter upon it will be prevented, but a very serious objection to this form of plate is the casting on it of ,necks or collars to receive the air-passages I. 'lhe joints between the necks and airpassages being very near, and exposed to the direct action of 4theiire, become very much expanded, and, as a natural consequence, bulge out open, and leak gaseous matter into the air-passages-a very serious defect. i l l v In my form of plate, the inclination beingI from the inner line of the air-passages I, presents' to the direct action of the tire the required radiating-surface, without the accumulation upon it of any nom-conducting subA stances.. This inclined part of plate G may beplain or corrugated, as shown in figs. 2 and 3.

That portion of the plate S upon which the air-passages I are arranged is made perfectly dat., so that ashes may accumulate upon it, and thereby make the joints between the plate G and air-passages self-packing and perfectly tight. In order to make the inclined surface ofnthe plate G a. more effectual heating-surface, I have arranged the annular iiue b. By this means I oblige all the products of combustion to pass outward over the inclined surface, andaround the air-passages, in their course to the exit-pipe. Thus my invention affords a large amount of perfect heating-surface, and horizontal joints for the air-passages, without the great-inconvenience of casting necks or collars upon any part ofthe tubular plate.

Another very important feature in 4my invention is extending theeylinder J J'downward from the plate K, by which arrangement I hold ,against the surface ofthe douiec the hot products of combustion, and oblige them, when cooled by radiation into the air-chamber d, to pass down below the mouth of the annular flue b, and mingle again with the hot currents arising from the fire, without, obstructingthe reiection of the ire upon the airpassages I.

Another feature of my inyention'is the cross-pipe or horizontal smoke-Hue Q, lthrough which the hot products of combustion pass inward to the exit-pipe R, in the centre of the furnace, for the purpose of increasing the heating-surface within the air-chamber d.'

Having thus described my invention, what I claim is l1. The combination, in an air-heating furnace, of the plate G, constructed substantially as described, n'ith the air-passages I I I I I and annular line 6, for the purpose 'as set forth. y

2. The combination, in an air-heating furnace,of the'dome e, air-passages I I I I I, and annular flue-), with the cylinder J J, o'r its equivalent, substantially as for the purpose 4set forth.

i GEORGE F. MERKLEE. Witnesses:

JOHN GALBRAITH, M. S. LAFoRen. 

